Project ALERT is an exemplary school-based curriculum designed to prevent or delay adolescents' use of alcohol, tobacco, and other drugs during middle school. In 1997, the National Institute on Drug Abuse funded ALERT PLUS, an expansion of the ALERT curriculum through 10th grade. The primary aim of this five-year project is to determine, by means of a randomized field trial, whether ALERT's middle-school effects can be sustained in the high-school years by adding booster lessons for 9th and 10th grade students. Early results from this trial, which involves clusters of 48 South Dakota high schools and their middle-school feeders, show that the revised middle-school curriculum improves on the original--curbing alcohol misuse, as well as cigarette and marijuana use. Preliminary analyses also indicate that the high school component helps maintain those results. In this application, we seek funds to evaluate the effectiveness of ALERT and ALERT PLUS during the period of emerging adulthood, when young people are considered to be at risk for increased levels of drug use and other risky behavior. Consistent with the strong links between drug use and behaviors affecting public health and productivity, we propose to expand our assessment of outcomes to include violent behavior, dropping out of high school, post-secondary educational attainment, and emotional distress. We will also assess the program's cost-effectiveness and cost benefit ratio over time. To carry out this agenda, we will collect data from the ALERT/ALERT PLUS panel after they transition out of high school (age 19) and two years later. The study has six specific aims: (1) Estimate effects of the ALERT/ALERT PLUS curricula on drug use at ages 19 and 21; (2) Estimate effects of the ALERT/ALERT PLUS curricula on drug use trajectories over six and eight years; (3) Estimate effects of the ALERT/ALERT PLUS curricula on dropping out and post-secondary educational achievement; (4) Estimate effects of the ALERT/ALERT PLUS curricula on emotional distress and on the relationship between drug use and emotional distress over time; (5) Estimate effects of the ALERT/ALERT PLUS curricula on violent behavior before and after age 19; and (6) conduct an economic evaluation of the ALERT/ALERT PLUS curricula.